scholarly journals ON THE METAMORPHIC MODIFICATION OF CR-SPINEL COMPOSITIONS FROM THE ULTRABASIC ROCKS OF THE PINDOS OPHIOLITE COMPLEX (NW GREECE)

2007 ◽  
Vol 40 (2) ◽  
pp. 781 ◽  
Author(s):  
A. Kapsiotis ◽  
B. Tsikouras ◽  
T. Grammatikopoulos ◽  
S. Karipi ◽  
H. Hatzipanagiotou
Keyword(s):  
Ultramafic Rocks ◽  
Cation Diffusion ◽  
Ophiolite Complex ◽  
Ferrian Chromite ◽  
The Common ◽  
Northwestern Greece ◽  
Common Association

Serpentinites and serpentinised ultramafic rocks from the Pindos ophiolite complex, northwestern Greece, contain Cr-spinel grains that are usually altered. The extent of alteration differs among Cr-spinels and two alteration trends can be distinguished. The most dominant is characterised by Cr-spinel overgrown by Cr-magnetite, while the second shows gradual replacement of Cr-spinel by ferrian chromite locally combined with Cr-magnetite development. Compared to cores, the altered rims are enriched in Fe and show elevated Cr# in both types of alteration, while they are impoverished in Mg and Al only at the second one. The common association of Crmagnetite with serpentine and ferrian chromite with chlorite provides insights to the metamorphic context of their formation through processes that include metasomatism by cation diffusion exchange

Leka Ophiolite Complex as analogy to the serpentinization-carbonation system on Mars.

2021 ◽  
Author(s):  
benjamin bultel ◽  
Agata M. Krzesinska ◽  
Damien Loizeau ◽  
François Poulet ◽  
Håkon O. Astrheim ◽  
...  
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Ground Truth ◽  
Ultramafic Rocks ◽  
Ophiolite Complex ◽  
Spectral Parameters ◽  
Thin Sections ◽  
Accessory Minerals ◽  
Mineral Assemblages ◽  
Alteration Minerals

<p>Serpentinization and carbonation have affected ultramafic rocks on Noachian Mars in several places called here serpentinization-carbonation systems (SCS). Among the most prominent SCS revealing mineral assemblages characteristic of serpentinization/carbonation is the Nili Fossae region [1]. Jezero crater – the target of the Mars 2020 rover –hosted a paleolake which constitutes a sink for sediments from Nili Fossae [1]. Thanks to the near infrared spectrometer onboard Mars2020 [2], the mission has the potential to offer ground truth measurement for other putative serpentinization/carbonation system documented on Mars. Several important aspects that may be addressed are: Do carbonates result from primary alteration of olivine-rich lithologies or are they derived by reprocessing of previous alteration minerals [3]? What is the composition? and nature of the protolith, which appear to be constituted of considerable amounts of olivine [4]? To reveal critical information regarding the conditions of serpentinization/carbonation, accessory minerals need detailed studies [1; 5]. In case of Jezero Crater, and serpentinization on Mars in general, the main alteration minerals are identified, but little is known about the accessory minerals.</p> <p>The Nili Fossae-Jezero system has potential analogues in terrestrial serpentinized and carbonated rocks, such as the Leka Ophiolite Complex, Norway (PTAL collection, https://www.ptal.eu). Here, distinct mineral assemblages record different stages of hydration and carbonation of ultramafic rocks [6].</p> <p>We perform petrological and mineralogical analyses on thin sections to characterize the major and trace minerals and combine with Near Infrared (NIR) spectroscopy measurements. A set of spectral parameters are defined and compare to spectral parameters previously used on CRISM and OMEGA data [1, 4, 7, 8]. We study the significance of the mineralogical assemblages including nature of accessory minerals. Effect of the presence of accessory minerals on the NIR signal is investigated and their potential incidence on the amount of H<sub>2</sub>/CH<sub>4</sub> production in mafic or ultramafic system is discussed [5].</p> <p>We started to apply the newly defined spectral parameters on several SCS on Mars. Results confirm local carbonation of earlier serpentinized rocks and suggest that different protoliths could have led to diversity of mineralogical associations in SCS on Mars. Multiple detection of brucite are also suggested for the first time on Mars. Altogether our results help to better describe key geochemical conditions of the SCS on Mars for habitability potential of the martian crust and Mars’s evolution.</p> <p><strong> </strong></p> <p>References:</p> <ul> <li>Brown, A. J., et al. <em>EPSL</em>1-2 (2010): 174-182.</li> <li>Wiens, R.C., et al.  <em>Space Sci Rev</em><strong>217, </strong>4 (2021).</li> <li>Horgan, B., et al. <em>Second International Mars Sample Return</em>. Vol. 2071. 2018.</li> <li>Ody, A., et al. <em>JGR: Planets</em>2 (2013): 234-262.</li> <li>Klein, F., et al. <em>Lithos</em>178 (2013): 55-69.</li> <li>Bjerga, A., et al. <em>Lithos</em>227 (2015): 21-36.</li> <li>Viviano-Beck et al, <em>JGR: Planets 11</em>8.9 (2013)</li> <li>Viviano-Beck et al, <em>JGR: Planets 119.6</em> (2014)</li> </ul>

A Model of Metabolic Supply-Demand Mismatch Leading to Secondary Brain Injury

2021 ◽  
Author(s):  
Jiangling Song ◽  
Jennifer A. Kim ◽  
Aaron Frank Struck ◽  
Rui Zhang ◽  
M. Brandon Westover
Keyword(s):  
Brain Injury ◽  
Mechanistic Model ◽  
Acute Brain Injury ◽  
Extracellular Potassium ◽  
Secondary Brain Injury ◽  
Proposed Model ◽  
The Common ◽  
High Level ◽  
The Brain ◽  
Common Association

Secondary brain injury (SBI) is defined as new or worsening injury to the brain after an initial neurologic insult, such as hemorrhage, trauma, ischemic stroke, or infection. It is a common and potentially preventable complication following many types of primary brain injury (PBI). However, mechanistic details about how PBI leads to additional brain injury and evolves into SBI are poorly characterized. In this work, we propose a mechanistic model for the metabolic supply demand mismatch hypothesis (MSDMH) of SBI. Our model, based on the Hodgkin-Huxley model, supplemented with additional dynamics for extracellular potassium, oxygen concentration and excitotoxity, provides a high-level unified explanation for why patients with acute brain injury frequently develop SBI. We investigate how decreased oxygen, increased extracellular potassium, excitotoxicity, and seizures can induce SBI, and suggest three underlying paths for how events following PBI may lead to SBI. The proposed model also helps explain several important empirical observations, including the common association of acute brain injury with seizures, the association of seizures with tissue hypoxia and so on. In contrast to current practices which assume that ischemia plays the predominant role in SBI, our model suggests that metabolic crisis involved in SBI can also be non-ischemic. Our findings offer a more comprehensive understanding of the complex interrelationship among potassium, oxygen, excitotoxicity, seizures and SBI.

The 1920s and 1930s Voodoo Craze

Making Gullah ◽  
2017 ◽  
Author(s):  
Melissa L. Cooper
Keyword(s):  
The Common ◽  
Black Magic ◽  
Travel Writers ◽  
Common Association ◽  
The Way

This chapter explores the 1920s and 1930s "voodoo craze" by examing the way that negative ideas about "Africa" and "Africans" during these years, and the prevelance of the common association between Africa and spiritual primitivism (superstitions, the belief in black magic, and dark rituals) became a prominent theme in assessments of Gullah folk's African connection. Using newspapers that circulated in popular migration destinations, films, plays, and travel writers' accounts to trace popular ideas about African survivals, this chapter charts a mounting obsession with southern black voodoo and superstition that reenergizes the debate over African survivals in the academe.

Early sulfide saturation is not detrimental to porphyry Cu-Au formation

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 519-524 ◽  
Author(s):  
Jingguo Du ◽  
Andreas Audétat
Keyword(s):  
Lower Crust ◽  
Silicate Melts ◽  
Mining District ◽  
Sulfide Saturation ◽  
Southeastern China ◽  
Porphyry Cu ◽  
Magmatic Sulfides ◽  
The Common ◽  
Common Association ◽  
Amphibole Fractionation

Abstract Ore-forming magmas are commonly considered to have been unusually metal rich. Because Cu and Au are strongly chalcophile, early sulfide saturation has been regarded as detrimental to porphyry Cu-Au mineralization. Here we demonstrate, based on amphibole-rich cumulate xenoliths and amphibole megacrysts from the Tongling porphyry(-skarn) Cu-Au mining district in southeastern China, that this view is not necessarily correct. Age data combined with petrological and geochemical evidence suggest that the mineralizing magmas at Tongling underwent significant fractional crystallization of amphibole, clinopyroxene, and magmatic sulfides in the middle to lower crust. The fact that the silicate melts nevertheless were able to produce substantial porphyry(-skarn) Cu-Au deposits implies that the formation of metal-rich cumulates at depth was not detrimental to their fertility. On the contrary, the common association of porphyry Cu (Au, Mo) deposits with high-Sr/Y magmas suggests that amphibole fractionation at depth even promotes the mineralization potential, despite the likely loss of metals.

Talc–carbonate alteration of ultramafic rocks within the Leka Ophiolite Complex, Central Norway

Lithos ◽  
2015 ◽  
Vol 227 ◽  
pp. 21-36 ◽  
Author(s):  
A. Bjerga ◽  
J. Konopásek ◽  
R.B. Pedersen
Keyword(s):  
Ultramafic Rocks ◽  
Ophiolite Complex

scholarly journals An Innovative Approach to Solving the Ergonomic Problem: Products’ Size Adjustment

2018 ◽  
Vol 2018 ◽  
pp. 105
Author(s):  
Ana Velkova
Keyword(s):  
Specific Problem ◽  
Main Issue ◽  
Innovative Approach ◽  
Master Thesis ◽  
Different Ages ◽  
The Common ◽  
Size Adjustment ◽  
Common Association

The use of ergonomic principles is imperative for the design of each contemporary product and its success on the market.  Despite the common association of ergonomics with comfort, especially with products related to sitting, this master thesis has its focus on products with adjustable sizes, setting a main goal to make this product durable and adaptable to various physical differences between the users (children at different ages). In this thesis, the use of bionic methods and principles provide innovative insight and solution to the main issue at hand, adapting the seat to different sizes with application of layers of material. In shaping the layers of material, a fractal design is used, an algorithm method that creates a mathematical dependence in solving the specific problem of different sizes. In this case it solves the correlation between the sizes of layers of the material. The results of these interdisciplinary researches are implemented and evaluated through a design of a child bike seat, by which they are turned into an ecological, recyclable and modern product.

scholarly journals Łódzkie obrachunki, czyli cztery ekslibrisy Brunona Schulza

Schulz/Forum ◽  
2018 ◽  
Author(s):  
Włodzimierz Rudnicki
Keyword(s):  
Detailed Analysis ◽  
Popular Belief ◽  
Graphic Art ◽  
The Common ◽  
Common Association

The author disagrees with a popular belief the Schulz’s bookplates have been made with the cliché-verre technique. He reconstructs the reasons for this misrecognition promoted by Jerzy Ficowski and Michał Kuna and the common association of Schulz’s graphic art with the Booke of Idolatry only, but in the first place makes a detailed analysis of the known bookplates, which allows him to claim that the techniques used were zincotype, drypoint, and heliogravure. The paper includes reproductions of four known bookplates by Schulz, with full descriptions made by the author.

The early Silurian pentamerid brachiopod Costistricklandia canadensis (Billings, 1859) and its biostratigraphic and paleobiogeographic significance

2002 ◽  
Vol 76 (4) ◽  
pp. 638-647 ◽  
Author(s):  
Jisuo Jin
Keyword(s):  
North America ◽  
Rocky Mountains ◽  
Baltic Region ◽  
Northern Rocky Mountains ◽  
The Third ◽  
Niagara Escarpment ◽  
The Common ◽  
Anticosti Island ◽  
The Baltic ◽  
Common Association

Costistricklandia is a common, easily recognizable pentamerid brachiopod in upper Llandovery to lowest Wenlock rocks of eastern Laurentia, Avalonia and Baltica. In this paper, the poorly known Costistricklandia canadensis (Billings) is re-described from the upper Telychian Rockway Dolomite of the Niagara Escarpment, Ontario. Compared to the relatively complete record of the Stricklandia-Costistricklandia evolution in the Welsh Borderland and the Baltic region, true representatives of the Stricklandia lens lineage are sporadic in North America, including those from the Merrimack Formation of Anticosti Island, the Red Mountain Formation of Alabama, the Hopkinton Formation of Iowa, and the Nonda Formation of the northern Rocky Mountains. Although the exact mode of speciation in the Stricklandia-Costistricklandia and the Pentamerus-Pentameroides transitions remains debatable, the common association of Costistricklandia and Pentameroides make them a useful concurrent biozone for correlating middle to upper Telychian rocks of North America and Europe. Paleobiogeographically, the Pentameroides-Costistricklandia Fauna marks the third major pulse of pentamerid faunal migration between Laurentia and its adjacent paleo-plates during the Early Silurian, following the limited intercontinental dispersal of the early Llandovery Virgiana Fauna and the quasi-cosmopolitan dispersal of the middle Llandovery Pentamerus Fauna.

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